title: Cramps and small-fiber neuropathy.
abstract: BACKGROUND
  Muscle cramps are a common complaint and are thought to arise from spontaneous discharges of the motor nerve terminal. Polyneuropathy is often causative, but small-fiber neuropathy (SFN) has not been assessed.
  
  
  METHODS
  We performed skin biopsies on consecutive patients with cramps but without neuropathic complaints. Twelve patients were biopsied, 8 with normal small-fiber sensation.
  
  
  RESULTS
  Seven patients had decreased intraepidermal nerve fiber density (IENFD), 2 with non-length-dependent loss. A cause for neuropathy was found in 1 patient with cramp-fasciculation syndrome. Creatine kinase was elevated in 8 patients, 4 with decreased IENFD. Muscle biopsy, performed in 8 patients, but was diagnostic in only 1, with McArdle disease.
  
  
  CONCLUSIONS
  Our data show that 60% of patients with muscle cramps who lack neuropathic complaints have SFN, as documented by decreased IENFD. Cramps may originate as local mediators of inflammation released by damaged small nerve that excite intramuscular nerves.
authors.affiliation: Department of Neurology, Division of Neuromuscular Disease, Washington University School of Medicine, Campus Box 8111, 660 South Euclid Avenue, St. Louis, Missouri 63110, USA. lopateg@neuro.wustl.edu
authors.forename: Glenn
authors.initials: G
authors.lastname: Lopate
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Streif
authors.forename: Matthew
authors.initials: M
authors.lastname: Harms
authors.forename: Christopher
authors.initials: C
authors.lastname: Weihl
authors.forename: Alan
authors.initials: A
authors.lastname: Pestronk
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D001706:Biopsy; D003402:Creatine Kinase / Q000378:metabolism; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009120:Muscle Cramp / Q000150:complications* / Q000175:diagnosis*; D009412:Nerve Fibers / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000150:complications* / Q000175:diagnosis*; D012867:Skin / Q000473:pathology
chemical_list: D003402:Creatine Kinase
keywords: muscle cramps; peripheral nervous system disease; skin biopsy; small-fiber neuropathy; unmyelinated nerve fibers